Multistep turbocharger arrangement

ABSTRACT

The invention relates to a multistep turbocharger arrangement ( 1 ) for an internal combustion engine with a high-pressure step ( 2 ), with a low-pressure step ( 3 ) which can be brought into operative connection to the high-pressure step ( 2 ) over a fluid passage system ( 4 ) which can be opened and closed, and with a control unit ( 5 ) for controlling the operative connection between the high-pressure step ( 2 )and the low-pressure step ( 3 ), wherein the control unit ( 5 ) and the fluid passage system ( 4 ) are integrated in an engine exhaust manifold ( 6 ) which is disposed between the high-pressure step ( 2 ) and the low-pressure step ( 3 ).

The invention relates to a multi-stage turbocharger arrangement as perthe preamble of claim 1.

Known turbocharger arrangements of said type have the disadvantage of acomplex design, with flaps, sleeves and control capsules which arehighly susceptible to wear, in particular as a result of a fragile crankdrive. Furthermore, uniform and continuous cross-sectional openings,which contribute to the regulating accuracy or quality of the regulatingcharacteristic, can only be realized to a limited extent.

It is therefore an object of the present invention to create amulti-stage turbocharger arrangement according to the preamble of claim1, the regulating system of which has improved regulating accuracy and asimplified and compact design.

Said object is achieved by means of the features of claim 1.

According to the invention, a simplified regulating unit for regulatingthe operative connection between the high-pressure turbocharger or thehigh-pressure stage and the low-pressure turbocharger or thelow-pressure stage of the turbocharger, which regulating unit isarranged in the manifold between the high-pressure stage and thelow-pressure stage and in which regulating unit are integrated all ofthe required flow ducts.

The subclaims relate to advantageous refinements of the invention.

Further details, advantages and features of the present invention can begathered from the following description of exemplary embodiments on thebasis of the drawing, in which:

FIG. 1 shows a first embodiment of a turbocharger arrangement, which isof two-stage design in the example, according to the present invention,

FIG. 2 shows a partially sectioned perspective partial view of theturbocharger arrangement according to FIG. 1,

FIG. 3 shows a sectioned partial view of the turbocharger arrangement ina first switching state,

FIG. 4 shows a view, corresponding to FIG. 3, of the turbochargerarrangement in a second switching state,

FIG. 5 shows a variant of the turbocharger arrangement in the switchingstate as per FIG. 4,

FIG. 6 shows an illustration corresponding to FIG. 3, of theturbocharger arrangement according to the invention in a third switchingstate, and

FIGS. 7 and 8 show the variant according to FIG. 5 in the switchingstate as per FIG. 6.

FIG. 1 illustrates a multi-stage turbocharger arrangement 1, which is oftwo-stage design in the example, for an internal combustion engine, inparticular a diesel or spark-ignition engine, wherein the engine ishowever not shown in FIG. 1 in order to simplify the illustration.

The turbocharger arrangement 1 has a high-pressure stage 2 and alow-pressure stage 3, which are formed in each case by a correspondinglydesigned turbocharger, of which in each case the turbine housing of theturbine is illustrated in the figures.

The high-pressure stage 2 and the low-pressure stage 3 can beoperatively connected to one another by means of an openable andclosable flow duct system 4, for which purpose a regulating unit 5 isprovided.

As can be seen in particular from FIGS. 1 and 2, the regulating unit 5is arranged in a manifold 6 between the high-pressure stage 2 and thelow-pressure stage 3. As is evident from a comparison of all thefigures, the flow duct system 4, which can be opened and closed by meansof the regulating unit 5, is also integrated in the manifold 6.

In the embodiment according to FIGS. 1 to 3 and 4 to 6, the regulatingunit 5 firstly has a regulating slide 7 which can be actuated by meansof an actuator 8, for which purpose the regulating slide 7 can be slidby means of an actuating rod 16, which is driven by the actuator 8,along an axis which runs through the actuating rod 16.

In the abovementioned embodiment, the regulating unit 5 also has abypass slide 9 which, in order to open and close a bypass duct 10, isarranged, like the regulating slide 7, in an axially slidable fashion ina housing 17 of the regulating unit 5. In the switching position whichis illustrated by way of example in FIG. 3, the bypass slide 9 closesthe bypass duct 10, with said bypass slide 9 being pre-loaded into itsclosed position, for example by means of a suitable spring.

In the first switching position, which can be seen in particular fromFIG. 3, the regulating slide 7 closes the direct path, which is formedby a flow duct 12 of the flow duct system 4, to the low-pressure stage3, with said first switching position being set at low engine speeds andtherefore low exhaust-gas flow rates. Therefore, in the first switchingposition of the regulating unit 5 as illustrated in FIG. 3, the exhaustgas expands in the high-pressure stage 2. This is indicated by thearrows P₁ in FIG. 3.

In the second switching position, as illustrated in FIG. 4, theregulating slide 7 opens the flow duct 12, or manifold cross section, ina preferably stepped fashion with increasing engine speed, such that theexhaust gas is conducted directly to the low-pressure stage 3, asindicated by the arrows P₂ in FIG. 4.

A corresponding switching position is illustrated in FIG. 5, whichillustrates a variant of the embodiment according to FIG. 4, since noseparate bypass slide is provided here. As shown by the illustrations ofFIGS. 4 and 5, the bypass duct 10 is closed in each case in said secondswitching position.

FIG. 6 illustrates the embodiment according to FIGS. 1 to 4 in a thirdswitching position. In said switching position, the regulating slide 7slides the bypass slide 9 back axially, as a result of which the bypassduct 10 or the bypass duct sections of the bypass duct 10 is/are openedup. A part of the exhaust gas can thus flow past the low-pressure spiralor the low-pressure turbine housing directly to the turbine housingoutlet (low-pressure stage), as indicated by the dashed arrow P_(3′).

A corresponding switching position of the variant according to FIG. 5 isillustrated in FIGS. 7 and 8, for which purpose the regulating slide 7′of said variant has a connecting duct 15 which can be seen in particularfrom FIG. 8 and which, as in the above-described design variant, opensthe bypass duct 10 such that it is possible for a part of the exhaustgas to be discharged directly to the turbine housing outlet of thelow-pressure stage 3.

To complement the above written disclosure of the invention, referenceis hereby explicitly made to the diagrammatic illustration of theinvention in FIGS. 1 to 8.

LIST OF REFERENCE SYMBOLS

1 Turbocharger arrangement

2 High-pressure stage

3 Low-pressure stage

4 Flow duct system

5 Regulating unit

6 Manifold/exhaust manifold

7 Regulating slide

7′ Regulating slide

8 Actuator

9 Bypass slide

10 Bypass

11 Cooling body

12, 13 Flow duct

14 Turbine housing section

15 Connecting duct

16 Actuating rod

17 Housing

P₁, P₂, P_(3′) Arrows

1. A multi-stage turbocharger arrangement (1) for an internal combustionengine, having a high-pressure stage (2), having a low-pressure stage(3) which can be operatively connected to the high-pressure stage (2) bymeans of an openable and closable flow duct system (4), and having aregulating unit (5) for regulating the operative connection between thehigh-pressure stage (2) and the low-pressure stage (3), wherein theregulating unit (5) and the flow duct system (4) are integrated in anengine exhaust-gas manifold (6) which is arranged between thehigh-pressure stage (2) and the low-pressure stage (3).
 2. Theturbocharger arrangement as claimed in claim 1, wherein the regulatingunit (5) has a regulating slide (7), by means of which an actuator (8)can be actuated.
 3. The turbocharger arrangement as claimed in claim 1,wherein the regulating unit (5) has a bypass slide (9), by means ofwhich a bypass (10) can be opened and closed and which is pre-loadedinto its bypass closed position.
 4. The turbocharger arrangement asclaimed in claim 3, wherein the bypass slide (9) can be moved into itsbypass open position.
 5. The turbocharger arrangement as claimed inclaim 1, wherein the regulating slide (7′) has a connecting duct (15)which can be flow-connected to the bypass (10) of the flow duct system(4).
 6. The turbocharger arrangement as claimed in claim 3, wherein thebypass slide (9) can be slid axially into its bypass open position.